NMR AND NQR STUDIES OF GLASS STRUCTURE

Li-6, Li-7, and Si29 high-field static NMR studies of lithium-potassium mixed-alkali glasses are reported. The fractional contribution to the spectral intensity of the various Q(n) units and the values of the chemical shift tensors for each of the sites are determined as a function of alkali composition. The dependence of the linewidths of the lithium spectra as a function of lithium-to-potassium ratio is evidence of like-alkali cation pairing in these glasses. The structure of borate glasses, pure vitreous B2O3, Li2O.B2O3, and 2Na2O.B2O3 was investigated with B-10 and B-11 NQR. Some structural sites that have not been resolved by NMR alone are found.